According to the conclusion of Kyoto Global Climate Conference, many countries have to cut their greenhouse gas emissions to below 6% to 1990 level in years between 2008 and 1012. With the power consumption for lighting purposes accounting for more than 20% of the livelihood-based energy, the development of energy saving lighting technology becomes even more important.
Light-emitting diode (LED), an optoelectronic semiconductor component that radiates by applying external voltage to simulate the electrons to produce lighting, provides the advantages of low power consumption and long service life, therefore prompting the worldwide researches and development of the related technologies. Practical applications currently are generally limited to low power indicator lamps, but with the active developments on high power LED technology in recent years. The illumination wattage is gradually improving, showing its potential for replacing conventional incandescent light bulb for lighting. Besides, the illumination efficiency of LED is soon expected to exceed 80 limens per watt, which is about six times the illumination efficiency of the conventional incandescent tungsten light bulb. In order to provide sufficient flux of light for lighting device, current designs include the assembly of arrayed LEDs with dozens of hundreds of LED lamps being packed together in wide range of applications from outdoor display to lighting.
However, with high power LED advancing, the heat generated by high power LED is also increased, and the dissipation of heat from LED becomes a critical problem. During operation, the illumination of LED lamps generates hot spots of high temperature in radiating area on high power LED, and currently, no solution is provided. This problem limits the development and applications of LED lamps. The poor heat dissipation of hot spots results to the overheating of LED lamps. When the junction temperature exceeds 120° C., the high temperature damages the LED lamps and leads to lower performance of LED, shorter service life, and even the peril of burnout. Hence, to promote the application of LED, the heat dissipation must be effectively settled.
Thus, it is desired to develop a LED device of high power and a means for effectively dissipate heat from a LED device for enhancing the performance, service lifespan, and reliability of lighting devices.